Prior to the present invention, a limitation of certain static eliminators is that they are only effective when the field of the charged object is undisturbed and in space (i.e., not in contact with other objects). When a charged object is in contact with or in close proximity to another object or surface, the field is disturbed and induced toward the other object or surface. For example, when a flat material such as a sheet of plastic is charged and placed in contact with another flat surface, the charge on the plastic sheet induces toward the other surface, causing the plastic sheet to cling to the flat surface. Concurrently, the voltage field on the opposite (non-contacting) side of the plastic sheet is generally not available for induction to a nearby static eliminator or for charge neutralization.
Static charge build-up can cause problems in a variety of settings, especially in the printing industry. In the case in which a sheet is moving across a flat surface or in contact with a roller, the voltage from the sheet is attracted toward the surface. The voltage is induced toward the surface. As such, there is no voltage on the upper side of the sheet, but only on the bottom side of the sheet induced toward the surface. A static field meter on the upper side often reads near zero levels.
In this case, static eliminators that are placed or swiped above the upper side of the sheet often do not eliminate the suppressed voltage (e.g., the voltage induced toward the surface) because little or no excess voltage exists above the sheet. Additionally, attempts to place a static eliminator below the sheet have posed a challenge in many instances. For example, placing a static eliminating cord or rod would interfere with the sheet's ability to move across the surface. Using static eliminating tape under the sheet results in tape that eventually gets abraded, damaged, or otherwise becomes ineffective after a certain amount of use.
Hence, a need exists for a static eliminator that can eliminate static on the induced surface side of a sheet. In particular, this need exists to efficiently eliminate static without interfering with the flow of the sheet or the machine on which it is used. A further need exists to do so without wearing down or abrading the ionizing points of the static eliminator.